﻿// Copyright (c) 2010-2014 SharpDX - Alexandre Mutel
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// -----------------------------------------------------------------------------
// Original code from SlimMath project. http://code.google.com/p/slimmath/
// Greetings to SlimDX Group. Original code published with the following license:
// -----------------------------------------------------------------------------
/*
* Copyright (c) 2007-2011 SlimDX Group
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* 
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/

using System.Globalization;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Serialization;

namespace Molten;

/// <summary>
/// Represents a bounding sphere in three dimensional space.
/// </summary>
[StructLayout(LayoutKind.Sequential, Pack = 4)]
[Serializable]
public struct BoundingSphere : IEquatable<BoundingSphere>, IFormattable
{
    /// <summary>
    /// The center of the sphere in three dimensional space.
    /// </summary>
    [DataMember]
    public Vector3F Center;

    /// <summary>
    /// The radius of the sphere.
    /// </summary>
    [DataMember]
    public float Radius;

    /// <summary>
    /// Initializes a new instance of the <see cref="BoundingBox"/> struct.
    /// </summary>
    /// <param name="center">The center of the sphere in three dimensional space.</param>
    /// <param name="radius">The radius of the sphere.</param>
    public BoundingSphere(Vector3F center, float radius)
    {
        this.Center = center;
        this.Radius = radius;
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="Ray"/>.
    /// </summary>
    /// <param name="ray">The ray to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref Ray ray)
    {
        float distance;
        return CollisionHelper.RayIntersectsSphere(ref ray, ref this, out distance);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="Ray"/>.
    /// </summary>
    /// <param name="ray">The ray to test.</param>
    /// <param name="distance">When the method completes, contains the distance of the intersection,
    /// or 0 if there was no intersection.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref Ray ray, out float distance)
    {
        return CollisionHelper.RayIntersectsSphere(ref ray, ref this, out distance);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="Ray"/>.
    /// </summary>
    /// <param name="ray">The ray to test.</param>
    /// <param name="point">When the method completes, contains the point of intersection,
    /// or <see cref="Vector3F.Zero"/> if there was no intersection.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref Ray ray, out Vector3F point)
    {
        return CollisionHelper.RayIntersectsSphere(ref ray, ref this, out point);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="Plane"/>.
    /// </summary>
    /// <param name="plane">The plane to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public PlaneIntersectionType Intersects(ref Plane plane)
    {
        return CollisionHelper.PlaneIntersectsSphere(ref plane, ref this);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a triangle.
    /// </summary>
    /// <param name="vertex1">The first vertex of the triangle to test.</param>
    /// <param name="vertex2">The second vertex of the triangle to test.</param>
    /// <param name="vertex3">The third vertex of the triangle to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref Vector3F vertex1, ref Vector3F vertex2, ref Vector3F vertex3)
    {
        return CollisionHelper.SphereIntersectsTriangle(ref this, ref vertex1, ref vertex2, ref vertex3);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="BoundingBox"/>.
    /// </summary>
    /// <param name="box">The box to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref BoundingBox box)
    {
        return CollisionHelper.BoxIntersectsSphere(ref box, ref this);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="BoundingBox"/>.
    /// </summary>
    /// <param name="box">The box to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(BoundingBox box)
    {
        return Intersects(ref box);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="BoundingSphere"/>.
    /// </summary>
    /// <param name="sphere">The sphere to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(ref BoundingSphere sphere)
    {
        return CollisionHelper.SphereIntersectsSphere(ref this, ref sphere);
    }

    /// <summary>
    /// Determines if there is an intersection between the current object and a <see cref="BoundingSphere"/>.
    /// </summary>
    /// <param name="sphere">The sphere to test.</param>
    /// <returns>Whether the two objects intersected.</returns>
    public bool Intersects(BoundingSphere sphere)
    {
        return Intersects(ref sphere);
    }

    /// <summary>
    /// Determines whether the current objects contains a point.
    /// </summary>
    /// <param name="point">The point to test.</param>
    /// <returns>The type of containment the two objects have.</returns>
    public ContainmentType Contains(ref Vector3F point)
    {
        return CollisionHelper.SphereContainsPoint(ref this, ref point);
    }

    /// <summary>
    /// Determines whether the current objects contains a triangle.
    /// </summary>
    /// <param name="vertex1">The first vertex of the triangle to test.</param>
    /// <param name="vertex2">The second vertex of the triangle to test.</param>
    /// <param name="vertex3">The third vertex of the triangle to test.</param>
    /// <returns>The type of containment the two objects have.</returns>
    public ContainmentType Contains(ref Vector3F vertex1, ref Vector3F vertex2, ref Vector3F vertex3)
    {
        return CollisionHelper.SphereContainsTriangle(ref this, ref vertex1, ref vertex2, ref vertex3);
    }

    /// <summary>
    /// Determines whether the current objects contains a <see cref="BoundingBox"/>.
    /// </summary>
    /// <param name="box">The box to test.</param>
    /// <returns>The type of containment the two objects have.</returns>
    public ContainmentType Contains(ref BoundingBox box)
    {
        return CollisionHelper.SphereContainsBox(ref this, ref box);
    }

    /// <summary>
    /// Determines whether the current objects contains a <see cref="BoundingSphere"/>.
    /// </summary>
    /// <param name="sphere">The sphere to test.</param>
    /// <returns>The type of containment the two objects have.</returns>
    public ContainmentType Contains(ref BoundingSphere sphere)
    {
        return CollisionHelper.SphereContainsSphere(ref this, ref sphere);
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere" /> that fully contains the given points.
    /// </summary>
    /// <param name="points">The points that will be contained by the sphere.</param>
    /// <param name="start">The start index from points array to start compute the bounding sphere.</param>
    /// <param name="count">The count of points to process to compute the bounding sphere.</param>
    /// <param name="result">When the method completes, contains the newly constructed bounding sphere.</param>
    /// <exception cref="System.ArgumentNullException">points</exception>
    /// <exception cref="System.ArgumentOutOfRangeException">
    /// start
    /// or
    /// count
    /// </exception>
    public static void FromPoints(Vector3F[] points, int start, int count, out BoundingSphere result)
    {
        if (points == null)
        {
            throw new ArgumentNullException("points");
        }

        // Check that start is in the correct range
        if (start < 0 || start >= points.Length)
        {
            throw new ArgumentOutOfRangeException("start", start, string.Format("Must be in the range [0, {0}]", points.Length - 1));
        }

        // Check that count is in the correct range
        if (count < 0 || (start + count) > points.Length)
        {
            throw new ArgumentOutOfRangeException("count", count, string.Format("Must be in the range <= {0}", points.Length));
        }

        var upperEnd = start + count;

        //Find the center of all points.
        Vector3F center = Vector3F.Zero;
        for (int i = start; i < upperEnd; ++i)
        {
            Vector3F.Add(ref points[i], ref center, out center);
        }

        //This is the center of our sphere.
        center /= count;

        //Find the radius of the sphere
        float radius = 0f;
        for (int i = start; i < upperEnd; ++i)
        {
            //We are doing a relative distance comparison to find the maximum distance
            //from the center of our sphere.
            float distance = Vector3F.DistanceSquared(ref center, ref points[i]);

            if (distance > radius)
                radius = distance;
        }

        //Find the real distance from the DistanceSquared.
        radius = MathF.Sqrt(radius);

        //Construct the sphere.
        result.Center = center;
        result.Radius = radius;
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> that fully contains the given points.
    /// </summary>
    /// <param name="points">The points that will be contained by the sphere.</param>
    /// <param name="result">When the method completes, contains the newly constructed bounding sphere.</param>
    public static void FromPoints(Vector3F[] points, out BoundingSphere result)
    {
        if (points == null)
        {
            throw new ArgumentNullException("points");
        }

        FromPoints(points, 0, points.Length, out result);
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> that fully contains the given points.
    /// </summary>
    /// <param name="points">The points that will be contained by the sphere.</param>
    /// <returns>The newly constructed bounding sphere.</returns>
    public static BoundingSphere FromPoints(Vector3F[] points)
    {
        BoundingSphere result;
        FromPoints(points, out result);
        return result;
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> from a given box.
    /// </summary>
    /// <param name="box">The box that will designate the extents of the sphere.</param>
    /// <param name="result">When the method completes, the newly constructed bounding sphere.</param>
    public static void FromBox(ref BoundingBox box, out BoundingSphere result)
    {
        Vector3F.Lerp(ref box.Min, ref box.Max, 0.5f, out result.Center);

        float x = box.Min.X - box.Max.X;
        float y = box.Min.Y - box.Max.Y;
        float z = box.Min.Z - box.Max.Z;

        float distance = float.Sqrt((x * x) + (y * y) + (z * z));
        result.Radius = distance * 0.5f;
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> from a given box.
    /// </summary>
    /// <param name="box">The box that will designate the extents of the sphere.</param>
    /// <returns>The newly constructed bounding sphere.</returns>
    public static BoundingSphere FromBox(BoundingBox box)
    {
        BoundingSphere result;
        FromBox(ref box, out result);
        return result;
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> that is the as large as the total combined area of the two specified spheres.
    /// </summary>
    /// <param name="value1">The first sphere to merge.</param>
    /// <param name="value2">The second sphere to merge.</param>
    /// <param name="result">When the method completes, contains the newly constructed bounding sphere.</param>
    public static void Merge(ref BoundingSphere value1, ref BoundingSphere value2, out BoundingSphere result)
    {
        Vector3F difference = value2.Center - value1.Center;

        float length = difference.Length();
        float radius = value1.Radius;
        float radius2 = value2.Radius;

        if (radius + radius2 >= length)
        {
            if (radius - radius2 >= length)
            {
                result = value1;
                return;
            }

            if (radius2 - radius >= length)
            {
                result = value2;
                return;
            }
        }

        Vector3F vector = difference * (1.0f / length);
        float min = Math.Min(-radius, length - radius2);
        float max = (Math.Max(radius, length + radius2) - min) * 0.5f;

        result.Center = value1.Center + vector * (max + min);
        result.Radius = max;
    }

    /// <summary>
    /// Constructs a <see cref="BoundingSphere"/> that is the as large as the total combined area of the two specified spheres.
    /// </summary>
    /// <param name="value1">The first sphere to merge.</param>
    /// <param name="value2">The second sphere to merge.</param>
    /// <returns>The newly constructed bounding sphere.</returns>
    public static BoundingSphere Merge(BoundingSphere value1, BoundingSphere value2)
    {
        BoundingSphere result;
        Merge(ref value1, ref value2, out result);
        return result;
    }

    /// <summary>
    /// Tests for equality between two objects.
    /// </summary>
    /// <param name="left">The first value to compare.</param>
    /// <param name="right">The second value to compare.</param>
    /// <returns><c>true</c> if <paramref name="left"/> has the same value as <paramref name="right"/>; otherwise, <c>false</c>.</returns>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool operator ==(BoundingSphere left, BoundingSphere right)
    {
        return left.Equals(ref right);
    }

    /// <summary>
    /// Tests for inequality between two objects.
    /// </summary>
    /// <param name="left">The first value to compare.</param>
    /// <param name="right">The second value to compare.</param>
    /// <returns><c>true</c> if <paramref name="left"/> has a different value than <paramref name="right"/>; otherwise, <c>false</c>.</returns>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool operator !=(BoundingSphere left, BoundingSphere right)
    {
        return !left.Equals(ref right);
    }

    /// <summary>
    /// Returns a <see cref="System.String"/> that represents this instance.
    /// </summary>
    /// <returns>
    /// A <see cref="System.String"/> that represents this instance.
    /// </returns>
    public override string ToString()
    {
        return string.Format(CultureInfo.CurrentCulture, "Center:{0} Radius:{1}", Center.ToString(), Radius.ToString());
    }

    /// <summary>
    /// Returns a <see cref="System.String"/> that represents this instance.
    /// </summary>
    /// <param name="format">The format.</param>
    /// <returns>
    /// A <see cref="System.String"/> that represents this instance.
    /// </returns>
    public string ToString(string format)
    {
        if (format == null)
            return ToString();

        return string.Format(CultureInfo.CurrentCulture, "Center:{0} Radius:{1}", Center.ToString(format, CultureInfo.CurrentCulture),
            Radius.ToString(format, CultureInfo.CurrentCulture));
    }

    /// <summary>
    /// Returns a <see cref="System.String"/> that represents this instance.
    /// </summary>
    /// <param name="formatProvider">The format provider.</param>
    /// <returns>
    /// A <see cref="System.String"/> that represents this instance.
    /// </returns>
    public string ToString(IFormatProvider formatProvider)
    {
        return string.Format(formatProvider, "Center:{0} Radius:{1}", Center.ToString(), Radius.ToString());
    }

    /// <summary>
    /// Returns a <see cref="System.String"/> that represents this instance.
    /// </summary>
    /// <param name="format">The format.</param>
    /// <param name="formatProvider">The format provider.</param>
    /// <returns>
    /// A <see cref="System.String"/> that represents this instance.
    /// </returns>
    public string ToString(string format, IFormatProvider formatProvider)
    {
        if (format == null)
            return ToString(formatProvider);

        return string.Format(formatProvider, "Center:{0} Radius:{1}", Center.ToString(format, formatProvider),
            Radius.ToString(format, formatProvider));
    }

    /// <summary>
    /// Returns a hash code for this instance.
    /// </summary>
    /// <returns>
    /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table. 
    /// </returns>
    public override int GetHashCode()
    {
        unchecked
        {
            return (Center.GetHashCode() * 397) ^ Radius.GetHashCode();
        }
    }

    /// <summary>
    /// Determines whether the specified <see cref="Vector4F"/> is equal to this instance.
    /// </summary>
    /// <param name="value">The <see cref="Vector4F"/> to compare with this instance.</param>
    /// <returns>
    /// <c>true</c> if the specified <see cref="Vector4F"/> is equal to this instance; otherwise, <c>false</c>.
    /// </returns>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool Equals(ref BoundingSphere value)
    {
        return Center == value.Center && Radius == value.Radius;
    }

    /// <summary>
    /// Determines whether the specified <see cref="Vector4F"/> is equal to this instance.
    /// </summary>
    /// <param name="value">The <see cref="Vector4F"/> to compare with this instance.</param>
    /// <returns>
    /// <c>true</c> if the specified <see cref="Vector4F"/> is equal to this instance; otherwise, <c>false</c>.
    /// </returns>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool Equals(BoundingSphere value)
    {
        return Equals(ref value);
    }

    /// <summary>
    /// Determines whether the specified <see cref="System.Object"/> is equal to this instance.
    /// </summary>
    /// <param name="value">The <see cref="System.Object"/> to compare with this instance.</param>
    /// <returns>
    /// <c>true</c> if the specified <see cref="System.Object"/> is equal to this instance; otherwise, <c>false</c>.
    /// </returns>
    public override bool Equals(object value)
    {
        if (!(value is BoundingSphere))
            return false;

        var strongValue = (BoundingSphere)value;
        return Equals(ref strongValue);
    }
}
